MoCA connected to Xfinity XB7 router kills my wired connection to my Windows 11 PC

Hi - My Xfinity gateway/router is in my home office upstairs, and the Xfinity extenders I have in other rooms of the house work intermittently, so I decided to set up MoCA to connect my smart TVs for streaming and my laptop in the kitchen. The MoCA devices are ScreenBeam model ECB66250. I set up the connections/filters according to the ScreenBeam instructions and enabled MoCA in my router settings, but when I power up the router I can connect to the Internet only using my wireless network. I have no ethernet connections available and MoCA still shows up as disabled at the top on my router settings. When I click that MoCA icon, it says no MoCA devices are connected. Obviously, I am doing something wrong, but I have tried a bunch of things and end up with no Internet connection at all.